Admin comments statistics is a plugin that allows WordPress site administrators to see detailed statistics and information about their comments and users. The plugin is really simple to install and use. With ACS you get: quick view of recent comment activity, comments frequency statistics, user’s comments detailed statistics, post’s comments detailed statistics, charts statistics, browser and OS statistics.
Admins can create a custom widget to display posts or users tops on the public side.
Also, it is easy to get in touch with the users using the plugin’s email system. Create mailing list based on users that commented and send HTML emails.